Philippine bomber planes and ground troops have hit a mountain stronghold of the al-Qaeda-linked Abu Sayyaf group in a new offensive targeting a key Malaysian terrorism suspect, officials said.

Filipino marines on Sunday found three as-yet unidentified bodies of suspected fighters scattered around an Abu Sayyaf jungle lair near Karawan village in Sulu province's Indanan town after OV-10 planes bombed the area, Lieutenant Colonel Randolph Cabangbang, a regional military spokesperson, said.

Amil Baanan, Sulu police operations chief, said the targets of the offensive included Malaysian Zulkifli bin Hir, also known as Marwan, a US-trained Malaysian engineer. Marwan has been hunted by United States and Philippine authorities for his alleged role in past bombings and terror attacks.

The troops were also after Singaporean fighter Muhammad Ali Bin Al-Rahman, also known as Muawiya, who is believed to be affiliated with the Southeast Asian network Jemaah Islamiyah.

Weapons found

Abu Sayyaf commander Umbra Jumdail, who has given refuge to Marwan and Muawiya in his jungle encampment, was also targeted, Banaan said.

Washington has offered a $5m reward for the capture or killing of Marwan, who is among Southeast Asia's most wanted terror suspects.

New intelligence indicated that the three terror suspects have been hiding in the heavily-forested Karawan area with about 30 Abu Sayyaf fighters, prompting the military to order the assaults, military officials said.

Marines found three assault rifles, a pistol and camouflage uniforms that were abandoned by the fighters as they were pursued, Cabangbang said.

Network

Marwan, who is believed to have provided bomb-making training and funds to Filipino fighters for years, is a key associate of Indonesian fighter Umar Patek, who was captured on January 25 in Pakistan's garrison town of Abbottabad, the same town where Osama bin Laden was killed in a US commando attack four months later.

Patek, whose real name is Anis Alawi Jaffar, had been hiding in Abu Sayyaf jungle encampments in the southern Philippines since 2003. He left a few years ago and ended up in Pakistan with his Filipino wife, who was also arrested, military and police officials said.

US-backed Philippine offensives have considerably weakened the Abu Sayyaf network, one of at least four Islamic insurgent groups operating in the country's southern islands.

About 380 of its fighters remain at large in the jungles of Jolo island, an impoverished Muslim region in Sulu province about 950km south of Manila, and in nearby Basilan and outlying islands.

The fighters have turned to kidnappings for ransom to sustain their operations and are believed to be holding a number of hostages, including a US citizen, two Malaysians, an Indian and a Japanese.